Dosing device in a tube filling machine

ABSTRACT

The invention relates to a dosing device in a tube filling machine, comprising a dosing chamber in a housing, said chamber having an inlet and an outlet for the medium which is to be dosed. At least one adjustable dosing piston whose volume in the dosing chamber is adjustable is provided in addition to a control bushing which is rotationably mounted in the housing, having at least one connecting channel which joins the inlet or the outlet to the dosing chamber when the control bushing is in a predetermined rotated position. The control bushing has a conical section which is sealingly arranged on a complementary conical section of the dosing chamber and which can be raised therefrom, in addition to an axial through hole in which the at least one dosing piston is displaceably guided. At least one section of the dosing chamber is disposed on the side next to the wider end of the conical section of the control bushing, so that the conical sections are pushed against each other when the pressure in the dosing chamber is increased as a result of movement of the dosing piston.

[0001] Translation of PCT/EP02/06326 as filed on Jun. 10, 2002

[0002] The invention concerns a tube filling machine dosing device having a dosing chamber which is formed in a housing with an inlet opening and an outlet opening for a medium to be dosed, at least one adjustable dosing piston by means of which the volume of the dosing chamber can be changed, and a control sleeve which is rotatably disposed in the housing and has at least one connecting channel which, in a predetermined rotated position of the control sleeve, connects the inlet opening or the outlet opening with the dosing chamber, wherein the control sleeve has a conical section which can be sealingly disposed on a complementary conical section of the housing and can be lifted therefrom.

[0003] A tube filling machine fills tubes with a predetermined dosed amount of a product or fill medium, and usually has a conveyor device formed as an endless belt or chain which carries a plurality of individual receptacles for each tube. The empty tubes are inserted into the receptacles of the conveyor device at a feed station and pass several work stations, including, in particular, a filling station and a subsequent closing station. The tubes are filled in the filling station via a filling pipe which is connected to a fill medium storage means via a dosing device. The filled tube is transported to the closing station where the upper tube end is closed.

[0004] A dosing device of conventional structure (DE 36 36 804 C1) comprises a housing which is connected to the fill medium storage means via an inlet opening and to the filling pipe via an outlet opening. A control sleeve is rotatably disposed in the housing, and a dosing chamber is formed inside the sleeve which has an access opening alternately connected to the inlet or outlet opening in dependence on the rotated position of the control sleeve. A dosing piston is displaceably disposed in the control sleeve and can draw a predetermined amount of the fill medium through the inlet opening into the dosing chamber when the outlet opening is closed and which can discharge it through the outlet opening when the inlet opening is closed thereby introducing it into the tube to be filled. The alternate opening and closing of the inlet and outlet openings is effected through rotation of the control sleeve.

[0005] The control sleeve is sealed relative to the housing via annular seals, and also has a conical section which abuts a complementary conical section of the housing. The control sleeve is closed at its one axial end and connected to an adjustment device through which it can be axially adjusted to separate the two conical sections.

[0006] It is usually necessary to replace the dosing piston when the amount of fill medium dose is to be changed, which is demanding and expensive since the tube filling machine is inoperative during this time. It is even more demanding when, after filling a first fill medium, change to another fill medium is to take place, since, for hygienic reasons, the filling unit and therefore also the dosing device must be completely cleaned of residues from the first fill medium. In one conventional solution to this problem, the dosing device is completely removed from the tube filling machine and cleaned by an operator, as a result of which the cleanliness depends on the quality of the work of the operator. Alternatively thereto, DE 36 36 801 C1 suggests axial displacement of the control sleeve through the adjustment device to such an extent that the housing, the control sleeve, and the dosing piston are brought from the normal working position to a cleaning position in which they are separated from another to expose the seals coming in contact with the fill medium being dosed. Through introduction of a cleaning liquid, the components and seals can be cleaned from the residues of the previously applied fill medium. The space required for the adjustment device is very large and it has turned out that the seals are subjected to great wear through the cleaning process and therefore must be replaced frequently which is also time-consuming and expensive.

[0007] It is the underlying purpose of the invention to create a dosing device of the above-mentioned type which is of compact construction and permits product change in a simple fashion.

[0008] This object is achieved in accordance with the invention with a dosing device of the above-mentioned type which has the characterizing features of claim 1.

[0009] In the inventive dosing device, the seal between the control sleeve and the housing is provided only or at least mainly through the sealing abutment of the conical sections of these components. In this fashion, a reliable and permanent seal between the control sleeve and the housing can be obtained when the two conical sections are pressed together. To release the two abutting conical sections, only the control sleeve must be slightly axially displaced thereby forming a gap between the conical sections which can be rinsed with a cleaning liquid. The control sleeve is subsequently displaced in the opposite direction until the two conical sections of the control sleeve and of the housing once more abut in a sealing fashion. In this manner, special elastic plastic seals can be avoided thereby also eliminating the danger of excess wear and the necessity of changing the seal.

[0010] A particularly compact design of the dosing device is obtained when the control sleeve has an axial opening in which at least one dosing piston is displaceably guided. A piston section of the dosing piston is received with tight fit and thereby sealed in the axial opening such that no special plastic seals are required.

[0011] At least portions of the dosing chamber are disposed to face the broader end of the conical section of the control sleeve. When the fill medium located in the dosing chamber is pressed via the dosing piston through the outlet opening into the filling nozzle and thereby into the tube, the pressure in the dosing chamber increases. In accordance with the invention, this pressure is used to press together the two conical sections of the control sleeve and the housing thereby ensuring the sealing effect between the housing and the control sleeve while also increasing the dosing accuracy for products of low viscosity.

[0012] Particularly good sealing properties can be obtained when the housing and/or the control sleeve and/or the dosing pistons are made from a ceramic material.

[0013] In a further development of the invention, two coaxial dosing pistons are provided of which the first dosing piston is formed as an annular piston guided in the axial opening of the control sleeve and having an axial bore in which the second dosing piston is displaceably guided.

[0014] This embodiment has the substantial advantage that the amount of fill medium supplied to the tube via the outlet opening of the dosing chamber can be changed in a simple fashion without changing the dosing piston. When the two coaxial dosing pistons are displaced as a unit, a relatively large amount of fill medium is supplied. When the outer first dosing piston of annular cross-section is stationary and only the inner second dosing piston is adjusted, a substantially smaller amount of fill medium is discharged. Alternatively, the inner second dosing piston may be stationary and only the outer annular first dosing piston is adjusted thereby supplying another amount of fill medium which is advantageously larger, preferably twice as much as the amount of fill medium supplied by the inner second dosing piston only. Each dosing piston preferably has its own drive, preferably in the form of a servo motor.

[0015] A further development of the invention provides that a rinsing chamber of an enlarged diameter is formed in the axial opening of the control sleeve in which a piston section of the first dosing piston can be received with play, wherein the rinsing liquid can be supplied to the rinsing chamber via at least one feed opening. In the cleaning position, the annular first dosing piston is displaced within the axial opening of the control sleeve such that its piston section is freely exposed in the rinsing chamber. The inner second dosing piston thereby remains stationary and therefore projects freely from the displaced first dosing piston such that it can also be cleaned upon introduction of a rinsing liquid.

[0016] When the control sleeve is axially displaced, the two conical sections come out of engagement and a gap is formed between the housing and the control sleeve which can be rinsed with a rinsing liquid to clean the dosing device. The rinsing liquid is preferably introduced through a separate supply opening which is formed in the foot region of the conical section of the housing.

[0017] In a possible embodiment of the invention, one end of the control sleeve projects into the dosing chamber and the channel connecting the dosing chamber to the inlet or outlet openings is formed in a straightforward manner by an axial groove which terminates at the end of the control sleeve.

[0018] Although one connecting channel or one axial groove is sufficient to optionally connect the inlet opening or the outlet opening to the dosing chamber, it is reasonable to provide at least two connecting channels or axial grooves, to obtain as small and rapid adjustment motion of the control sleeve as possible, the channels being disposed such that there is no position in which both the inlet opening and the outlet opening are simultaneously connected to the dosing chamber.

[0019] The conical section of the control sleeve is preferably formed on the axial end projecting into the dosing chamber, wherein the axial grooves are also provided in the conical section of the control sleeve.

[0020] Further details and features of the invention can be extracted from the following description of an embodiment with reference to the drawing:

[0021]FIG. 1 shows a vertical section through an inventive dosing device in the initial position;

[0022]FIG. 2 shows a top view onto the dosing device in accordance with FIG. 1, with removed lid;

[0023]FIG. 3 shows the dosing device of FIG. 1 at the end of the suction cycle;

[0024]FIG. 4 shows a top view onto the dosing device of FIG. 3, with removed lid;

[0025]FIG. 5 shows the dosing device of FIG. 1 at the end of the supply cycle,

[0026]FIG. 6 shows a top view onto the dosing device of FIG. 5, with removed lid;

[0027]FIG. 7 shows the dosing device of FIG. 1 at the end of the suction cycle in a first alternative operating mode;

[0028]FIG. 8 shows the dosing device of FIG. 1 at the end of the suction cycle in a second alternative mode of operation; and

[0029]FIG. 9 shows the dosing device of FIG. 1 in the cleaning position.

[0030] In accordance with FIG. 1, a dosing device 10 in a tube filing machine has a housing 11 which is held on a support 17 (not shown in detail). An axial bore 12 is formed in the housing 11 which extends in a smooth conical manner in the upper region of the housing 11. The interior of this conically extending section 12 a of the axial bore 12 defines a dosing chamber 13 which is sealingly closed at the upper end of the housing 12 by a lid 16.

[0031] A radial inlet opening 14 is formed in the housing 11 in the central region of the conical section 12 a, through which a fill medium can be introduced into the dosing chamber 13 (indicated by arrow M). A radial outlet opening 15 is formed in the housing 11 diametrally opposite to the inlet opening 14, through which the fill medium can be pressed from the dosing chamber 18 to a filling nozzle (not shown in FIG. 5) as indicated by arrow F. A radial bore 11a is formed in the lower region of the conical section 12 a, i.e. in the transition region between the axial bore 12 and the conical section 12 a thereof, which is connected to a supply of rinsing liquid (not shown).

[0032] A control sleeve 18 is inserted into the axial bore 12 of the housing 11, which is seated with a lower circular cylindrical section with tight fit in the axial bore 12, and has a conically extending section 18 a at the upper end which has the same slant angle as the conical section 12 a of the axial bore 12. The dosing chamber 13 is formed between the upper end of the conical section 18 a of the control sleeve 18 and the lid 16.

[0033]FIG. 1 shows the control sleeve 18 in its lower position, in which its conical section 18 a sealingly abuts the conical section 12 a of the axial bore 12. The conical section 18 a of the control sleeve 18 has two axial grooves 18 b and 18 c which terminate at its upper front side (FIG. 2), and whose width substantially corresponds to the width of the inlet opening 14 and outlet opening 15 respectively and which extend to the bottoms thereof. The two axial grooves 18 b and 18 c are offset in the peripheral direction of the control sleeve by an angle of approximately 135°. When the control sleeve 18 is in the position shown in FIGS. 1 and 2, in which the axial groove 18 b connects the inlet opening 14 to the dosing chamber 13, the connection between the dosing chamber 13 and the outlet opening 15 is interrupted. When the control sleeve 18 is turned from the position shown in FIG. 2 by an angle of approximately 45° in a clock-wise direction, the connection between the inlet opening 14 and the dosing chamber 13 is interrupted and the connection between the dosing chamber 13 and the outlet opening 15 is opened.

[0034] A central axial opening 18 d is formed in the control sleeve 18 which widens in the lower section of the control sleeve 18 to a rinsing chamber 18 e having a larger diameter. The rinsing chamber 18 e is connected to a supply of rinsing liquid (not shown) through a radial supply opening 21.

[0035] A first dosing piston 19 of annular cross-section is displaceably inserted into the axial opening 18 d of the control sleeve 18 and has a piston section 19 a at its upper end which seats with tight fit in that axial opening 18 d of the control sleeve 18. The width of the first dosing piston 19 is reduced below the piston section 19 a. The dosing piston 19 penetrates through the lower end of the control sleeve 18 at a bore 18 f and is guided therethrough.

[0036] A central axial bore 19 b of constant cross-section is formed in the first dosing piston 19, in which a second dosing piston 20 is displaceably disposed. The second dosing piston 20 has an upper piston section 20 a, which seats sealingly and with tight fit in the axial bore 19 b of the first dosing piston 19. The lower end of the piston section 20 a of the second dosing piston 20 joins to a piston rod section 20 b which penetrates through a lower guiding and cover plate 22 of the first dosing piston 19 in a sealing fashion, and is guided through same. The axial bore 19 b of the first dosing piston 19 has a supply opening 23 at its lower end which is also connected to the supply of rinsing liquid.

[0037] The first dosing piston 19 can be displaced as a unit together with the second dosing piston 20 in the axial bore 18 d of the control sleeve 18. It is, however, also possible to move each dosing piston 19 or 20 independently of the respective other dosing piston.

[0038] The function of the dosing device and its possible modes of operation are exemplarily described below.

[0039]FIGS. 1 and 2 show the initial position of a dosing process. The two dosing pistons 19 and 20 and their piston sections 19 a and 20 a are each in an upper end position and the control sleeve 18 is adjusted within the housing 11 such that the inlet opening 14 is connected to the dosing chamber 13 through the axial groove 18 b. The connection between the dosing chamber 13 and the outlet opening 15 is interrupted. Departing from this position, the two dosing pistons 19 and 20 are downwardly displaced as a unit within the axial bore 18 d of the control sleeve 18, thereby increasing the volume of the dosing chamber 13 (FIG. 3). The vacuum created thereby draws the fill medium through the inlet opening 14 and the axial groove 18 b into the dosing chamber 13. When the dosing pistons 19 and 20 have reached their lower end position, the control sleeve 18 is turned by 45° thereby interrupting the connection between the inlet opening 14 and the dosing chamber 13 and producing a connection between the dosing chamber 13 and the outlet opening 15 (FIG. 6). The two dosing pistons 19 and 20 are then moved together in an upward direction thereby reducing the volume of the dosing chamber 13 and forcing the fill medium out of the dosing chamber 13 via the axial groove 18 c through the outlet opening 15. The associated pressure increase within the dosing chamber 13 also acts on the control sleeve 18 and forces it downwards such that the conical section 18 a of the control sleeve 18 is pressed against the conical section 12 of the axial bore 12 of the housing 11 thereby increasing the sealing effect. At the end of the stroke of the dosing pistons 19 and 20, they are again in their upper end position (FIG. 5) and the supply process terminates. The control sleeve 18 is then turned by 45° in the opposite direction to again reach the initial position of FIG. 1 from which a new dosing process can be started.

[0040] When the amount of the fill medium dosed by the two dosing pistons 19 and 20 is too large, the dosing pistons 19 and 20 can also be adjusted independently of each other. FIG. 7 shows a first example thereof. Departing from the initial position of FIG. 1 in which the dosing chamber 13 is connected to the inlet opening 14 through the axial groove 18 b, only the outer annular first dosing piston 19 is downwardly displaced rather than both dosing pistons 19 and 20, with the inner second dosing piston 20 remaining stationary. Supply medium is thereby drawn through the inlet opening 14 and the axial groove 18 b into the dosing chamber 13, but the volume enlargement of the dosing chamber 13 is less and the drawn amount of fill medium is accordingly reduced.

[0041] Turning of the control sleeve 18 and returning the outer annular first dosing piston 19 into the initial position can force the fill medium located in the dosing chamber 13 out through the axial groove 18 c and the outlet opening 19.

[0042]FIG. 8 shows an alternative mode of operation, with which the outer annular first dosing piston 19 is stationary and only the inner second dosing piston 20 is downwardly displaced to draw the fill medium into the dosing chamber 13. The volume enlargement of the dosing chamber 13 thereby achieved is even less than in the above-mentioned example in which only the outer first dosing piston 19 was displaced and even a smaller fill medium amount is thereby dosed. In this case as well, the fill medium is pressed out of the dosing chamber 13 after turning the control sleeve 18 by returning the second dosing piston 20 to its initial upper position.

[0043] When the fill medium to be dosed is changed, the dosing device 10 must be cleaned. Towards this end, the components can be moved to a so-called cleaning position (see FIG. 9). The outer first dosing piston 19 is displaced within the axial opening 18 d of the control sleeve 18 in a downward direction until its piston section 19 a is freely disposed in the rinsing chamber 18 e of the control sleeve 18. The piston section 20 a of the inner second dosing piston 20 projects upwardly out of the axial bore 19 b of the first dosing piston 19 and lies freely within the axial opening 18 d of the control sleeve 18, which, in turn, is slightly upwardly displaced relative to the housing 11 such that its conical section 18 a is separated from abutment with the conical section 12 a of the axial bore 12 of the housing 11. Cleaning or rinsing liquid is introduced into the rinsing chamber 18 e through the supply opening 21 (indicated by arrow C₁), to rinse and thereby clean the piston section 19 a of the outer first dosing piston 19. Cleaning or rinsing liquid is also introduced through the supply opening 23 into the axial bore 19 b of the first dosing piston 19 as indicated by arrow C₂ and flows through the axial bore 19 b to exit at the upper end and rinse the freely disposed piston section 20 a of the inner second dosing piston 20.

[0044] The axial displacement of the control sleeve 18 relative to the housing 11 forms an annular gap between the conical section 12 a of the axial bore 12 of the housing 11 and the conical section 18 a of the control sleeve 18, the lower end of which is connected to the opening 11 a through which the cleaning or rinsing liquid is introduced (indicated by arrow C₃). Cleaning and rinsing liquid can also be introduced through the inlet opening 14 (arrow C₄). The cleaning and rinsing liquid introduced in this fashion can also be discharged through the outlet opening 15 (indicated by arrow C₅).

[0045] When the cleaning process is finished, the outer first dosing piston 19 is upwardly displaced within the control sleeve 18 until its piston section 19 a is sealingly disposed with tight fit in the axial opening 18 d of the control sleeve 18. Adjustment of the control sleeve 18 in an axial direction brings the two conical sections 12 a and 18 a into sealing abutment such that the initial position shown in FIG. 1 is once more obtained. 

1 through 9 cancelled.
 10. A dosing device for a dosing medium in a tube filling machine, the device comprising: a housing defining a dosing chamber, said housing having an inlet opening and an outlet opening for receiving and discharging the dosing medium; a control sleeve rotably disposed in said housing, said control sleeve having at least one connecting channel to connect said inlet opening or said outlet opening to said dosing chamber at respective predetermined rotated positions of said control sleeve, said control sleeve having a conical section which can be sealingly disposed on a complementary conical section of said housing and which can be lifted therefrom, wherein at least one portion of said dosing chamber is defined by a wide end of said conical section, said control sleeve also having an axial bore; a first dosing piston, said first dosing piston formed as an annular piston guided within said axial bore of said control sleeve, said annular piston having an axial bore; and a second dosing piston displaceably guided within said annular piston axial bore, said second dosing piston disposed coaxially with respect to said first dosing piston, wherein said first dosing piston and said second dosing piston are displaceable to change a volume of said dosing chamber, wherein said control sleeve conical section is pressed against said housing conical section when a pressure in said dosing chamber is increased in response to motion of at least one of said first dosing piston and said second dosing piston.
 11. The dosing device of claim 10, wherein said first and said second dosing piston can be adjusted as a unit.
 12. The dosing device of claim 10, wherein said first and said second dosing piston can be adjusted independently of each other.
 13. The dosing device of claim 10, wherein each of said first and said second dosing pistons has its own servomotor drive.
 14. The dosing device of claim 10, wherein said axial bore of said control sleeve defines a rinsing chamber with enlarged diameter in which a piston section of the said first dosing piston can be received with play, wherein said rinsing chamber can be supplied with rinsing liquid through at least one first supply opening.
 15. The dosing device of claim 10, wherein rinsing liquid can be introduced through at least one second supply opening of said housing into a space formed between said housing and said control sleeve when said control sleeve conical section is lifted.
 16. The dosing device of claim 10, wherein at least one of said housing, said control sleeve, said first dosing piston, and said second dosing piston are made from ceramic material.
 17. The dosing device of claim 10, wherein said at least one connecting channel is formed by an axial groove.
 18. The dosing device of claim 17, wherein at least two axial grooves are provided in said control sleeve through which said inlet opening or said outlet opening can be connected to said dosing chamber.
 19. The dosing device of claim 18, wherein said two axial grooves are formed in said conical section of said control sleeve. 